Home » Sentinel-6: ‘Dog kennel’ satellite tv for pc to measure sea-level rise

Sentinel-6: ‘Dog kennel’ satellite tv for pc to measure sea-level rise

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By Jonathan Amos
BBC Science Correspondent

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media captionSentinel-6 has fastened photo voltaic panels. Moving photo voltaic wings may disturb its measurements
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A satellite tv for pc that will likely be crucial to understanding of local weather change will launch on Saturday from California.

Sentinel-6 Michael Freilich will grow to be the first technique of measuring the form of the world’s oceans.

Its information will observe not solely sea-level rise however reveal how the good mass of waters are transferring across the globe.

Looking considerably like a canine kennel, the subtle 1.3-tonne satellite tv for pc is because of elevate off from the Vandenberg base at 09:17 native time (17:17 GMT).

The Sentinel is a joint endeavour between Europe and the US, and can proceed the measurements which have been made by a succession of spacecraft, referred to as the Jason-Topex/Poseidon collection, going again to 1992.

These earlier missions have proven unequivocally that sea ranges globally are rising, at a fee in extra of 3mm per 12 months over the 28-year interval. And their most up-to-date information even suggests there may be an acceleration underneath method, with ranges recorded as going up at over 4mm per 12 months.

About half of the measured world sea-level rise on Earth is from warming waters and thermal growth, a key driver of which is world warming. The different half is coming from melting ice.

About one-third of the measured world sea-level rise on Earth is from the growth of warming water, a key driver of which is local weather change. The relaxation is from melting ice.

Sentinel-6, like all of the satellites earlier than it, will use a radar altimeter to evaluate the peak of the oceans.

This instrument sends down a microwave pulse to the floor after which counts the time it takes to obtain the return sign, changing this into an elevation.

Sentinel-6 will, nonetheless, fly with a a lot improved functionality, which can enable it to see extra clearly what seas are doing proper up in opposition to coastlines; and likewise how inland water options – rivers and lakes – are behaving.

picture captionThe document has been constructed by 4 earlier satellites. The baton now passes to Sentinel-6

Why is ocean top so essential?

Elevation is a key parameter for oceanographers. Just as floor air stress reveals what the environment is doing above, so ocean top will betray particulars concerning the behaviour of water down beneath.

The information provides clues to temperature and salinity. When mixed with gravity info, it’s going to additionally point out present path and pace.

The oceans retailer huge quantities of warmth from the Sun; and the way they transfer that vitality across the globe and work together with the environment are what drive our local weather system.

But having the longest attainable document of change is crucial.

“The longer that time series, the better able we are to separate out the natural climate signals from the forced ones, from the human signal,” defined European Space Agency mission scientist Craig Donlon.

“It means we can run climate models backwards and then, through a validation process, have confidence that when we run them forwards we have some predictive skill.”

Sea-level trends
picture captionThe rise in sea stage isn’t uniform. Some areas of the globe have been rising very quick

Why is the 3mm determine somewhat deceptive?

The oceans are usually not rising on the similar fee in all places. There are elements of the world the place the elevation exceeds 1cm per 12 months.

This is because of a mess of things, together with modifications in ocean circulation, modifications in warmth content material, and the uneven dispersal of meltwater from ice sheets.

It’s somewhat recognised incontrovertible fact that the discharge from mighty glaciers, resembling Thwaites Glacier in Antarctica, has the best impact on ocean top at far distances.

“Sea-level rise is not uniform; it’s really important to recognise this,” Christine Gommenginger, from the UK’s National Oceanography Centre in Southampton, informed BBC News.

“It’s the regional sea-level budgets that we’re now targeting. Global sea-level rise – fine, we know about this. But it’s the local picture we want, and the altimetry can give us this.”

Glacier meltwater dispersal
picture captionMeltwater from the large Thwaites glacier impacts sea stage a good distance away from Antarctica

Who makes use of sea-surface top information?

Oceanographers and climatologists, clearly. But the information is of supreme significance to the climate forecasters as nicely.

In the return sign is details about the state of the ocean – about how tough it’s, which speaks additionally to the energy of the winds.

The ocean and its connection to the environment is maybe greatest illustrated in hurricanes. These storms get their vitality from heat tropical water which an altimeter can sense by the best way the ocean floor bulges.

And it is satellites like Sentinel-6 that give forewarning of an El Niño occasion, which sees heat waters within the western Pacific shift eastwards. This units off a worldwide perturbation in climate methods, redistributing rainfall and bumping up temperatures.

“Other users include ship routers – they don’t want their vessels to go through storms; they want to avoid big waves,” stated Remko Scharroo, from the intergovernmental climate company Eumetsat. “With the Sentinel-6 altimeter, we will also see the eddies in the ocean, and if you’re a ship router this information will tell you how to go with the current, not against it.”

It goes with out saying that coastal and flood defence planning relies on the elevation information. No new nuclear energy station could be constructed with out understanding the place excessive tide and storm surges may attain many years into the long run.

Flood risk
picture captionThe info is used to plan coastal and flood defences many years into the long run

What’s within the particular identify?

The “Sentinel” moniker is the identify given to all of the satellites within the European Union’s Copernicus Earth-observation programme, of which this mission is part.

Its quantity exhibits that it’s the sixth within the collection of various sensor sorts deliberate for the community.

The identify Michael Freilich commemorates the previous director of the US house company Nasa’s Earth sciences division who died earlier this 12 months. He was an oceanographer by background and was instrumental in placing collectively the worldwide partnership behind the mission.

“Mike Freilich exemplified the commitment to excellence, generosity of spirit and the unmatched ability to inspire trust that made so many people across the world want to work with Nasa, to advance big goals on behalf of the planet and its people,” commented Thomas Zurbuchen, who heads Nasa’s science directorate.

Rocket launchpicture copyrightESA
picture captionSentinel-6 Michael Freilich will likely be taken to an orbit 1,336km above the Earth

[email protected] and comply with me on Twitter: @BBCAmos

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